This invention has to do with the operation of a clutch between an internal combustion engine and a rotating element. It is described as applied to a vehicle-mounted earth drill, of the type shown generally in Rassieur U.S. Pat. No. 3,527,309, but its usefulness is not limited to such a device. It does have particular utility as applied to the system illustrated in Rassieur U.S. Pat. No. 5,085,280, as will be described.
In a conventional clutch arrangement to which the illustrative embodiments of the prior art of FIG. 1 and of the mechanism of the present invention are described as applied, a pressure plate assembly is mounted on a flywheel of an internal combustion engine and a clutch plate is mounted on an output shaft. The pressure plate assembly includes an axially movable pressure plate and powerful compression springs which bias the pressure plate into engagement with the clutch plate. Radially inwardly extending fingers are pivoted in the pressure plate assembly to retract the pressure plate against the bias of the pressure plate springs when the fingers are moved in a direction toward the clutch plate, to disengage the pressure plate from the clutch plate. The fingers are moved against the bias of the pressure plate springs by a throw-out bearing, slidably mounted on the output shaft. The throw-out bearing is moved by a yoke fixedly mounted on a shaft journalled in bearings in the clutch housing. One end of the shaft projects from the housing, and a clutch throw-out (lever) is mounted on the outer end of the shaft. When the throw-out is moved, it rotates the shaft, rotating the yoke and moving the throw-out bearing against or away from the pressure plate assembly fingers. It is desirable to keep the throw-out bearing clear of the fingers, which are rotating with the pressure plate, hence relative to the throw-out bearing, when the clutch is engaged. When the clutch is in a power train from the engine to a rotating member such as an earth drill, it is conventional to provide manual means for operating the throw-out, to engage and disengage the clutch. In the system described in U.S. Pat. No. 5,085,280, the manual system is overridden by a mechanical throw-out mechanism in case of emergency, but in ordinary operation, the throw-out is operated by moving a long handle up to engage the clutch, and down to disengage it.
A typical prior art clutch operating and lock-out assembly is illustrated in FIG. 1. The clutch lock-out assembly 1 includes a clutch throw-out 3, which in FIG. 1 is shown as connected to the shaft journalled in and projecting from a clutch housing 2; a connecting rod 4; an intermediate linkage 5 that includes an intermediate linkage lever 17; an operating rod 6, a retracting spring 7 mounted at one end on a spring bracket 8 connected to a fixed frame of the machine and connected at its other end to a spring ear 9 connected to the operating rod 6; a lever 10 from which a stub shaft or axle 12 projects; a pillow block 11 in which the axle 12 is journaled; a gudgeon 14 operatively connected to the operating rod 6 and to the lever 10, and a handle 15 secured at one end to the lever 10. The handle 15 has a short dog leg 16 at an end at which it is secured to the lever, a long straight reach, and, at its outer end, a knob 18.
The gudgeon 14 is positioned between the axle 12 and the end of the lever to which the handle is connected. When the handle is pulled down, rocking the lever lo around the axle 12 against the bias of the pressure plate springs and the much weaker bias of the spring 7, pulling the lever 17 in a direction toward the handle 18, the gudgeon 14 moves to a point below the axle 12 sufficiently far so that the bias of the pressure plate springs and the spring 7 keeps the lever and handle from moving back up. There are several disadvantages inherent in the system described. As a practical matter, the amount of throw is limited, because when the gudgeon 14 moves below the axle 12, in order to ensure that the handle remains down, the gudgeon has to move back toward the lever 17, thus moving the lever 17 back toward the clutch engaging condition. This means that the lever 17 must be made relatively short so as to ensure sufficient travel of the throw-out 3. The handle is not locked against upward movement. Also, with the automatic mechanical disengagement of the clutch in response to the actuation of a switch, as described in U.S. Pat. No. 5,085,280, the rigid rod 6 is moved against the bias of the spring 7, causing the handle 15 to move downwardly rapidly, which could disconcert an operator.
One of the objects of this invention is to provide a clutch operating mechanism in which a handle is positively restrained against movement from a throw-out position.
Another object is to provide such a mechanism which permits a longer throw in the same or less amount of space than is possible with a conventional clutch operating mechanism.
Another object is to provide such a system in which the automatic disengagement of the clutch will not affect the handle.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.